Phase I developed and tested a new software-based divided attention test of cognitive performance that used color, language-free graphic displays. The test ran on any DOS based-PC without external hardware or controls. The test was more sensitive to alcohol-induced impairment than previous hardware-based tests (mean breath alcohol levels of 0.045 percent and 0.079 percent). The main advantages of performance On- Line are that it can run on any soft-ware platform without external device, is not biased to alpha-numeric characters, can be self- administered, and is designed to be low cost (approximately $400). The Phase II project standardizes the test (Performance On-Line) through a series of analytical and laboratory studies which document the test's reliability and validity in detecting alcohol use, drug use, pharmaceutical use, and sleep loss and fatigue. The goal is to develop the test and analytical procedures to that both are acceptable for worksite research and applications. Four clinical research studies examine variables to confirm test validity: tolerance development to alcohol, cognitive impairment to a CNS sedative (alprazolam) and a CNS stimulant (dextroamphetamine), and the effects of sleep loss and fatigue. The project also develops analysis procedures for test users, including reliability and signal detection ROLC analyses. On-line interactive procedures with scientific and corporate subscribers will be refined which enable the development of continuously updated baseline norms on monitor size, age, gender, occupation, vision corrections, and height/weight ratio. A worksite evaluation will be proposed in a Phase III application.